>Eric Smith <[email protected]> wrote: >DEC MK11-B Field Maintenance Print Set, October 1977
Thanks, Eric! I was just about to post that I discovered it's also in the PDP-11/04 maintenance print on Bitsavers, although it's not in the 11/34 print - go figure... I didn't actually need the schematic, although I certainly used it this time. The H7441 has a giant inductor (L1 in the schematic) that's physically bolted to the PCB. It a U-channel thing that looks like a transformer but is actually just a big 30+ amp choke. Some PCB layout guy decided it was a good idea to run the +5V output and ground traces directly under this choke so, unless it's elevated above the PCB, it will short the output! I think it must have originally had some kind of rubber or fiber washers underneath it, but in mine the washers had disintegrated and were nowhere to be found. I could tell that it was shorted somewhere, but I kept thinking that it must be a bad capacitor or a shorted crowbar, and I'm embarrassed to say that it took me more than an hour to figure out that it was the frame on the choke. I carved up a rubber grommet with an X-acto to make some spacers and now it's as good as new. Bob
